Agree with another commenter that documentation is an issue. If you're a developer, it's not too bad. It uses a kind of homebrew model/view/template python backend that might baffle you for a while.

If you don't need to modify it or integrate it too much with your bank, e-commerce sites, cash registers, etc then it pretty much works out of the box.

Odoo came from a fully open sourced project years ago and is getting more and more closed and expensive over time as they go upmarket. If you really want to own your data I'm not sure that's a good direction.

There is a fork called Flectra that is usually about a version behind Odoo but reintegrates a lot of the paid features of Odoo for free, but its documentation and community is even smaller.